fun box(): String {
  var r: String = ""
  when {
    EQEQ(arg0 = r, arg1 = "").not() -> { // BLOCK
    }
    else -> r = r.plus(other = "O")
  }
  when {
    EQEQ(arg0 = r, arg1 = "O") -> r = r.plus(other = "K")
  }
  return r
}
